The objective of our studies of membrane and virus structure is to analyze the assembly and stability of macromolecular aggregates which exemplify the processes of normal and pathological growth and differentiation. The molecular interactions that stabilize the spirally wrapped myelin membranes are being characterized by coordinated X-ray and neutron diffraction, electron microscopic and chemical studies on purified myelin and intact nerves which have been modified by in vitro treatment or by pathological conditions. The structural basis of electrical and chemical connections between cells is being investigated by coordinated X-ray diffraction and electron microscope studies on isolated mouse liver gap junctions. The stability and hydration of small viruses and other macromolecular complexes are being characterized by combined diffraction and physico-chemical methods. New X-ray and neutron diffraction techniques are being developed to investigate the molecular dynamics and structure of intact and reconstituted cellular assemblies. BIBLIOGRAPHIC REFERENCES: D.A. Kirschner and D.L.D. Caspar. "Myelin Structure Transformed by Dimethylsulfoxide", Proc. Nat. Acad. Sci. U.S.A. (1975) 72, No. 9. D.A. Kirschner, D.L.D. Caspar, B.P. Schoenborn and A.C. Nunes. "Neutron Diffraction Studies of Nerve Myelin", Brookhaven Symposium in Biology, No. 27 (1975) in press.